As stated above, the undertone is what matters, whether its warm or cool not the fairness or darkness of the skin. the easiest way to check--if your veins show through your skin as blue, you're cool-toned (winter or summer season), if they show as green, you're warm-toned (spring or autumn season).
Yellow gold, red gold and bronze are generally better for warm toned people and plat, silver and white gold for cool toned. But there are golds that look good on cool toned people. Generally lower carat--don't try 18k and above.
This is most important near your face--for a ring or bracelet or a necklacenot near your face, not as key.
A little tarnish makes silver warmer and then warm toned people can wear it. Not a lot so that the silver is black, but just a little so that it gets goldish. Rhodium dipped silver won't do this and generally won't suit those with warm toned skin.